Modelling of point and non-point nutrient loadings from a watershed

An integrated model was developed to estimate the loadings of nutrients and organic matter from point and non-point sources in a watershed by use of the software Pamolare. The model accounted for the loadings from industrial and municipal wastewaters, atmospheric deposition and runoff from the drainage area. We tested the model using data from Lake Glumsø, Denmark, with a drainage area of about 1054.9 ha and with known annual loadings into the lake in 1978, 1982 and 2000. The model was first calibrated against one year's record, followed by one year's validation, and finally a prognosis scenario was performed. The predictions by the model were consistent with the observations. Thus, the model may be applicable for estimating nutrient loadings from drainage areas, when observations in general are not available. It can also be used to examine the current conditions and test the effects of management and planning scenarios within a watershed.